Electric multiphase tubular heating structure having hollow refractory conductors and all terminals at one structure end



Jan. 7, 1969 K A. POHLER ET A1. 3,420,986

ELECTRIC MULTIPHASE TUBULAR HEATING STRUCTURE HAVING HOLLOW REFRACTORY CONDUCTORS AND ALL TERMINALS AT ONE STRUCTURE END Filed Dec. 19, 1966 frewfw, 6455 992,95; Jfff/y United States Patent Otitice 3,420,986 Patented Jan. 7, 1969 A 11,493/ 65 U.S. Cl. 219-553 Int. Cl. H05b 3/10; H05!) 3/34; H05b 3/54 6 Claims ABSTRACT OF THE DISCLOSURE Electric heating structures wherein a plurality of elongated thin wires are interlaced into hollow conductors which are combined into an elongated hollow tubular heater structure having an axial length greater than the tubular wi-dth and all terminal ends at one axial end thereof. The terminal ends of the hollow heater structure are joined into a heating circuit for connection to heating current source. Intermediate portions of the elongated hollow conductors are supported by either one or more transversely extending other hollow heating conductors or by at least one transversely extending elongate-d insulating support. yIn a very effective tubular heating structure of the invention formed of a plurality of such hollow conductors, each heater phase thereof is formed of a plurality of such hollow axially extending conductors connected in series with each other.

It has already been suggested that electric heating conductors of tungsen and/ or molybdenum be constructed of thin wire woven, knitted or interlaced into a thin hollow heating conductor. However, up to the present this 1954 suggestion has found only negligible practical application.

Among the objects of the invention are practical hollow tubular refractory heating structures -formed of hollow elongated conductors combined into such hollow heating structures having all of its terminal end portions disposed at one end of such tubular heating structure and connected into a common energizing circuit.

The foregoing and other objects of the invention will be best understood from the following ydescription of the exemplications thereof, reference being had to the accompanying drawings, wherein:

FIG. 1 shows a perspective view of one heating structure of the invention;

FIG. l-A is a perspective view of an end portion of one of the hollow conductors of such heating structure;

FIG. 2 is a perspective view of one portion of the heater body of the heating structure of FIG. 1; and

FIG. 3 is another perspective view similar to FIG. 1 of a further example of ya heating structure of the invention.

A 1954 publication of the Wipperfurth Company described ldifferent forms of hollow tubular electric heater conductors made of thin refractory wires of tungsten, molybden-um and their alloys. It states that the heating conductor could be made of other known high temperature melting metals such as tantalum and niobium 'alloys and chrome-nickel ibase alloys. Such hollow heating conductors could be used for heating of high temperature ovens as a heater filament in vacuum tubes or as a vacuum tube grid which is `heated by the nearby cathode.

In accordance with the invention, an axially extending tubular heating structure 10 of the invention such as shown in FIG. 1 is formed of a plurality of narrow elongated hollow tubular conductors 11, an example of which is shown in FIG. l-A, which extend along the axis of the heater structure 10. The axial length of tubular heating structure 10 is greater than its transverse width or diameter. The axially extending elongated hollow conductor 11 of the heater structure 10 are shown interwoven with transversely crossing similar hollow conductors 12, for example, in the way indicated in FIG. 2 to form a heating conductor cable or cable-shaped heater structure 10. The individual hollow tubular conductors 11 yand 12 are each made of interlaced thin ductile wires of refractory metals such as molybdenum. tungsten or tungsten-molybdenum alloys. However, these hollow conductors may also be formed of other refractory metals such as tantalum, niobium and their other alloys and also of chrome-nickel base alloys.

The tubular heating structure 10 of FIG. 1 may be formed of two transversely extending and interwoven sets of hollow conductors 11 and 12, an example of which is shown in FIG. l-A. Each of the hollow conductors 11 and 12 may be woven or knitted out of thin tungsten wires 0.1 to 0.3 mm. .thick by known techniques used in making textile threads into a hollow tubular conductor the exterior of which consists of interlaced thin conductor wires of such small thickness.

FIG. l shows one tubular hollow heating structure 10 of the invention formed of such hollow elongated conductors 11 and 12 which are combined into interwoven hollow conductor structure such as shown in FIG. 2. It consists of two semi-tubular heater sections or halves 10 spaced from each other on opposite sides by gaps 13. The two heater halves 10 have all terminal ends at one end thereof which are secured to two strong, solid supporting and connecting collar sections 14 of refractory metal having terminal and/ or :support ends 15. At the opposite end, the two semi-tubular heater sections 10 are joined in a common circuit by a solid metallic collar 15 which like the conductor half-collars 14 are made of refractory metal such as molybdenum or tungsten. The opposite strong support structures 14, 15 of the heater structure 10 serve to support it in its operative position within the heating apparatus :shown while its woven hollow conductors 11, 12 are loosely supported in the operative position within the furnace.

FIG. l shows the tubular heater structure 10 as being axially relatively short `for the sake of illustration only. Such tubular heater structure 10 has its opposite terminal elements 14 at one end of the tubular heating conductor 10, the opposite ends of which are interconnected as by electric welding to common strong conductor ring or collar 15. In practice it has been found that a hollow heating conductor structure 10 formed with such loosely supported elongated hollow tubular conductors of the type shown and described in connection with FIGS. l, l-A and 2 will operate at temperatures above 2000 C. without any noticeable embrittlement of the thin conductor wires of its hollow tubular conductors 11 and 12.

In FIG. 3 is shown another exemplication of a heater structure 22 of the invention. Elongated hollow tubular conductors 11, asimilar to hollow conductors 11, 12 of FIG. 2, are shaped into a tubular heating structure 22 having upper terminal end 23 and an opposite end 24. Intermediate longitudinal sections of the hollow elongated tubular conductors 11 are folded lengthwise parallel to each other to form the tubular heating structure 22 wherein `many adjacent longitudinal hollow conductor sections are serially connected with each other. The adjacent longitudinal sections of the hollow con-ductor 11 may be supported in the desired arcuate formation, for example by elongated ceramic supporting rings 26 to which the individual hollow conductors are secured, for instance, by refractory wires 28. In the particular hollow heater structure 22 of FIG. 3, multiphase current is supplied to three terminal portions 31, 32 and 33 shown at its upper end region. The ceramic supporting rings 26 separate the individual hollow conductors 11 of tubular structure 22 into three equal different arcuate heater phases 31, 32, 33. These three individual conductor phases 31, 32, 33 are energized by similar hollow supply terminal members 311, 32-1 and 33:*1 of similar hollow tubular conductor portions welded thereto and energized by a source of three-phase energizing current of a conventional type. Instead of connecting the Ihollow conductors of the heating structure 22 into a triangular closed poly-phase circuit they may be connected to the supply conductors 311, 32-1 and 33-1 as a star-shaped circuit.

The principles underlying the invention described in connection with specific exemplications will suggest other modifications and applications thereof. It is accordingly desired that the appended claims shall not be limited to specic examples shown or described herein.

What is claimed is:

1. In an electric metallic heating structure extending along an axis between opposite structure ends,

a plurality of different elongated tubular conductor sections of a hollow tubular metallic conductor extending along said axis adjacent to each other between said opposite structure ends,

eac-h hollow tubular conductor consisting of thin interlaced metallic tilaments all confined to its tubular exterior region;

a plurality of elongated support elements traversing, engaging and supporting intermediate portions of said dierent adjacent conductor sections in the shape of an elongated hollow tubular heater structure of relatively large diameter and an axial length greater than said diameter,

said tubular heater structure having all their different polarity terminal end portions disposed at one end of said tubular heater structure which terminal end portions constitute support elements carrying loosely the major length of each said adjacent tubular conductor sections,

all the opposite end portions of all said tubular conductor sections being joined into common conductor paths extending `between said terminal end portions.

2. In an electric metallic heating structure as claimed in claim 1,

said plurality of elongated support elements constituting additional similar conductor sections engaging and supporting intermediate portion of said first mentioned adjacent conductor sections extending betwee said opposite structure ends. 3. In an electric metallic heating structure as claimed in clairn 2,

the opposite ends of said additional conductor sections being joined into said common conductor paths. 4. In an electric metallic heating structure as claimed in claim 1,

said elongated support elements including at least one insulating support member. 5. In an electric metallic heating structure as claimed in claim 4,

said plurality of hollow adjacent conductor sections constituting at least two distinct segmental heater regions, with the opposite ends of adjacent different conduct-or sections being serially connected in a common conductor path between different of said terminal end portions. 6. In an electric metallic heating structure as claimed in claim 5,

intermediate portions of said different conductor sections being held spaced and supported by at least two of said elongated insulating support members.

References Cited UNITED STATES PATENTS 2,422,477 7/ 1947 Driver 338-214 2,922,867 1/ 1960 Crump 219-545 X 3,152,246 10/1964 Van Icuren et al. 219--553 3,178,665 4/1965 Matheson et al 338-299 3,257,492 6/1966 Westeren 13-31 3,274,374 9/ 1966 Matheson et al. 219--426 GEORGE HARRIS, Primary Examiner.

V. Y. MAYEWSKY, Assistant Examiner.

U.S. Cl. X.R. 

